McAfee seems to have a given a new twist to the global warming debate. It blames us for harming the environment every time we hit the delete button to get rid of spam email. Last year alone saw 62 trillion spam emails and these had the same impact on environment as 3.1 million passenger cars or 2.4 million US homes.

While antispam product seller, McAfee might have its own reasons for highlighting the environmental impact of spam, several other popular online activities are bound to be bigger cans of carbon. With about 15-22% (depending on which analyst firm you ask) of the world?s population on the Internet, our online digital carbon footprint is bound to be huge.

Spam?s carbon footprint, in fact, should be smaller among the 78 exabytes (or 78 quintillion bytes) of data estimated to be transmitted over the Internet last year. It is even smaller than the average legitimate email, since spam mails are typically smaller than the regular emails and require less energy from servers that transfer them from one location to another.

Moreover, deleting spam mail is only a small part of the overall production of spam and can reduce green house gases only in that proportion. End user might not be able to save a big chunk as the spam has been generated somewhere and sent out over routers and traveled the world before landing in our inbox. So, spam filter can save only a part of the energy used.

Here?s a look at the five most popular online activities that can be bigger culprits of environment.

Search

Internet search, in fact, was the first online activity which attracted environmentalists? ire. A Alex-Wisner Gross of Havard announced publicly that each Google search generates 7 grams of CO2. This means two Google searches produced the same amount of carbondioxide as bringing an electric kettle to a boil. After some protests from Google, he accepted that the amount of energy consumed by an average Google query is 0.2 grams of CO2. Interestingly, Google claims that user?s personal computer will take more energy than Google uses to answer the query.

Blogs and micro-blogs

As blogs become pervasive and integral part of our online lives, energy consumed in posting and reading can not be far behind. Currently, 27.9 million US Internet users have a blog they update at least once per month, and they represent 14% of the Internet population. By 2013, 37.6 million users will update their blogs at least monthly. Growth numbers are even bigger at micro-blogging sites like Twitter. It saw a 131% increase in US visitors in March and 700% in February respectively over the previous month, according to online traffic tracker comScore.

Social networking and video sharing

Social networking and video sharing would certainly consume more energy than sending a spam mail, which is even smaller than a typical legitimate email. As everything online, from gaming to email, adopts social networking features, it is obviously counted the most popular activities. According to Comscore, visits to the social networking sites in India increased 51% from the previous year to more than 19 million visitors at the end of last year. And these users are spending a lot of time last year, For instance, Facebook users spent 178 minutes on the site last month on average.

Job searches

Job sites rank among the more popular online and even economic slowdown hasn?t affected the business of major job sites in India like Naukri.com in 2009.

Porn

Most user studies don?t track it, but cyberporn is clearly one of the more popular activities online and the resulting carbon emissions are bound to be high.

If one agrees with McAfee study, most of us will be guilty of a heavy carbon footprint, enough to put a petrol or diesel guzzling vehicle to shame. Even then it wont?t help to revert to physical world equivalents. If we were to stop all the spam in the world, for instance, at least some of the spammers will revert to junk mail. This means cutting more trees and burning more fuel to deliver these letters!